Moons Moons: Moons are `fossils" into a planet's past.

The major, named moon systems are: Earth: Luna (The Moon) Mars: Deimos, Phobos Jupiter: Adrastea, Amalthea, Ananke, Callisto, Carme, Elara, Europa, Ganymede, Himalia, Io, Leda, Lysithea, Metis, Pasiphae, Sinope, Thebe Saturn: Atlas, Calypso, Dione, Enceladus, Epimetheus, Helene, Hyperion, Iapetus, Janus, Mimas, Pan, Pandora, Phoebe, Prometheus, Rhea, Telesto, Tethys, Titan Uranus: Ariel, Belinda, Bianca, Cordelia, Cressida, Desdemona, Juliet, Miranda, Oberon, Ophelia, Portia, Puck, Rosalind, Titania, Umbriel Neptune: Despina, Galatea, Larissa, Naiad, Nereid, Proteus, Thalassa, Triton Pluto: Charon (note: Pluto/Charon form a binary system, but Charon is the smaller so it is classed as the moon of Pluto) New, smaller moons are being discovered all the

 time with recent space missions.

The total count of moons (as of 12/18/2001) are: Mercury - 0 moons Mars - 2 moons Uranus - 20 moons Venus - 0 moons Jupiter - 28 moons Neptune - 8 moons Earth - 1 moon Saturn - 30 moons Pluto - 1 moon Moons range in shape from highly irregular to spheres. Their shape reflects their formation history, irregular objects are ill-formed moons (captured asteroids or comets) or pieces of a larger moon, spherical objects were once molten spheres, probably at the time of their formation. Moons of Mars: Deimos & Phobos We speculate, from their irregular appearances and low mean densities, that Deimos and Phobos, are captured asteroids. Both Deimos and Phobos are saturated with craters. Deimos has a smoother appearance caused by partial filling of some of its craters. Moons of Jupiter: Jupiter has 63 confirmed moons as of Jan 2009, i.e. moons with known orbits around Jupiter. Eight of these moons are regular, meaning they have prograde, nearly circular orbits.

They are composed of the four Galilean satellites, plus the inner or Amalthea group: Adrastea is a typical small moon Metis is the innermost known satellite of Jupiter Amalthea is one of Jupiter's smaller, irregular moons, an example of moon collecting dust from another moon (Io) The remaining 55 moons are irregular, they have a mixture of prograde and retrograde orbits with high inclinations and eccentricities. Jupiter's regular satellites are believed to have formed from a circumplanetary disk, a ring of accreting gas and solid debris analogous to a protoplanetary disk. The irregular satellites are substantially smaller objects with more distant and eccentric orbits. They form families with shared similarities in orbit (semi-major axis, inclination, eccentricity) and composition; it is believed that these are at least partially collisional families that were created when larger (but still small) parent bodies were shattered by impacts from asteroids captured by Jupiter's gravitational field. Moons of Saturn: The moons of Saturn are numerous and diverse, ranging from tiny moonlets less than 1 kilometer across to the enormous Titan, which is larger than the planet Mercury.

Saturn has sixty-two moons with confirmed orbits, fifty-three of which have names, and only thirteen of which have diameters larger than 50 kilometers. Saturn has seven moons that are large enough to become spherical. Twenty-four of Saturn's moons are regular satellites; they have prograde orbits not greatly inclined to the Saturn's equatorial plane. These include the seven major satellites, four small moons which exist in a Trojan orbit with larger moons, two mutually co-orbital moons and two moons which act as shepherds of Saturn's F Ring. Two other known regular satellites orbit within gaps in Saturn's rings. The relatively large Hyperion is locked in a resonance with Titan. The remaining regular moons orbit near the outer edge of the A Ring, within G Ring and between the major moons Mimas and Enceladus. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn. The remaining thirty-eight, all small except one, are irregular satellites, whose orbits are much farther from Saturn, have high inclinations, and are mixed between prograde and retrograde. These moons are probably captured minor planets, or debris from the breakup of such bodies after they were captured, creating collisional families.

The irregular satellites have been classified by their orbital characteristics into the Inuit, Norse, and Gallic groups, and their names are chosen from the corresponding mythologies. The largest of the irregular moons is Phoebe, the ninth moon of Saturn, discovered at the end of the 19th century. The rings of Saturn are made up of objects ranging in size from microscopic to hundreds of meters, each of which is on its own orbit about the planet. Thus, a precise number of Saturnian moons cannot be given, as there is no objective boundary between the countless small anonymous objects that form Saturn's ring system and the larger objects that have been named as moons. At least 150 moonlets embedded in the rings have been detected by the disturbance they create in the surrounding ring material, though this is thought to be only a small sample of the total population of such objects. Daphnis drifts through the Keeler gap Atlas the second of Saturn's known satellites, orbits near the outer edge of the A-ring Enceladus is one of the innermost moons of Saturn.

Enceladus reflects almost 100 percent of the sunlight that strikes it and has evidence of internal heating and recent resurfacing effects Hyperion is one of the smaller moons of Saturn. It has a pock-marked body and is the largest irregularly shaped satellite ever observed.

Iapetus is one of the stranger moons of Saturn, its leading side is dark with a slight reddish color while its trailing side is bright Dione is the densest moon of Saturn other than Titan, and has several usual characteristics: 1) has a rocky core and ice crust, 2) is heavy cratering on trailing hemisphere, 3) has bright, wispy features Rhea is the largest airless satellite of Saturn that has different regions with different crater sizes indicating that parts of the moon have undergone resurfacing since formation Mimas is one of the innermost moons of Saturn with a very large impact crater that came close to fracturing the moon Tethys is an icy body similar in nature to Dione and Rhea Phoebe is the last of the known satellites of Saturn and orbits in a retrograde direction (opposite to the direction of the other satellites' orbits) in a plane much closer to the ecliptic than to Saturn's equatorial plane. Thus, Phoebe may be a captured asteroid with a composition unmodified since the time it was formed in the outer Solar System.

Moons of Uranus: Uranus, the seventh planet of the Solar System, has 27 known moons, all of which are named after characters from the works of William Shakespeare and Alexander Pope. William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other spherical moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda). The remaining moons were discovered after 1985, either during the Voyager 2 flyby mission or with the aid of advanced Earth-based telescopes. A montage of Uranus' large moons and one smaller moon: from left to right Puck, Miranda, Ariel, Umbriel, Titania and Oberon. Uranian moons are divided into three groups: thirteen inner moons, five major moons, and nine irregular moons. The inner moons are small dark bodies that share common properties and origins with the planet's rings. The five major moons are massive enough to have achieved hydrostatic equilibrium (they were once molten spheres), and four of them show signs of internally driven processes such as canyon formation and volcanism on their surfaces.

The largest of these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about 20 times less massive than Earth's Moon. Uranus's irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at great distances from the planet. Ariel is a relatively small satellite and is the brightest moon of Uranus Miranda with a jumbled surface unlike anything in the Solar System, indicates evidence of violent past with possible multiple shattering and reassembly Titania is the largest moon of Uranus and is marked by a few large impact basins Moons of Neptune: Neptune has thirteen known moons, by far the largest of which is Triton, discovered by William Lassell just 17 days after the discovery of Neptune itself. Over a century passed before the discovery of the second natural satellite, called Nereid. Neptune's moons are named for minor water deities in Greek mythology. Unique among all large planetary moons, Triton is an irregular satellite, as its orbit is retrograde to Neptune's rotation and inclined relative to the planet's equator.

The next-largest irregular satellite in the Solar System, Saturn's moon Phoebe, is only 0.03% Triton's mass. Triton is massive enough to have achieved hydrostatic equilibrium and to retain a thin atmosphere capable of forming clouds and hazes. Both its atmosphere and its surface are composed mainly of nitrogen with small amounts of methane and carbon monoxide. Triton's surface appears relatively young, and was probably modified by internally driven processes within the last few million years. The temperature at its surface is about 38K. Inward of Triton are six regular satellites, all of which have prograde orbits in planes that lie close to Neptune's equatorial plane. Some of these orbit among Neptune's rings. The largest of them is Proteus. Neptune also has six outer irregular satellites, including Nereid, whose orbits are much farther from Neptune, have high inclinations, and are mixed between prograde and retrograde. The two outermost ones, Psamathe and Neso, have the largest orbits of any natural satellites discovered in the Solar System to date.

Proteus is one of the darkest objects in the Solar System Saturn's Moons: Facts About the Ringed Planet's Satellites Saturn's Moons: Facts About the Ringed Planet's Satellites By Nola Taylor Redd, Space.com Contributor | June 30, 2016 05:48pm ET MORE The comparitive sizes of some of Saturn's biggest moons are shown. Credit: NASA/JPL/David Seal At least 62 moons travel around Saturn. They come in a variety of sizes and compositions, from almost pure ice to rocky material, as well as a combination of both. Their journeys around the ringed planet range from half an Earth day to just over four Earth years. One of Saturn's moons, Titan, makes up 96 percent of the mass orbiting the planet. Scientists think that Saturn's system may have originally housed two such moons, but the second broke up, creating the debris that formed the rings and smaller, inner moons. Another theory suggests that the system originally housed several large moons, similar to Jupiter's Galilean moons , but two fused into Titan. The violent collision could have scattered the debris that would have later drawn together into the smaller moons.

The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft. The north polar hood can be seen on Titan (3,200 miles or 5,150 kilometers across) and appears as a detached layer at the top of the moon here. Image released Dec. 22, 2011. Credit: NASA/JPL-Caltech/Space Science Institute Some of the moons travel inside the gaps of the rings, clearing paths through the debris. Others orbit farther out. Several of the moons interact with one another, with their orbits moving in resonance with each other. Larger moons may trap smaller moons, keeping them nearby. Sixteen of the moons are tidally locked, with one face permanently turned toward Saturn. The first moon was discovered in 1655. Over the next 200 years, the other seven major satellites were spotted. By 1997, astronomers on Earth had found 18 moons in orbit around the planet. The close orbit of NASA's Cassini mission , along with advances in technology for Earth-based telescopes, enabled the discovery of the rest.

In 1847, British astronomer Sir John Herschel suggested that the moons of Saturn take their names from the Titans. The mythical siblings of the Greek god Cronus — Saturn to the Romans — the Titans battled the Olympian gods and lost. Once the names of the Titans were used, the moons began to be called after other characters from Roman and Greek mythology. Only 53 of Saturn's moons have names; the rest are identified by a numerical designation relating to their year of discovery. [ PHOTOS: The Rings and Moons of Saturn ] Let's look at the eight major moons of Saturn: Titan Titan is the largest of Saturn's moons and the first to be discovered. Titan is the only moon in the solar system known to have a significant atmosphere. Nitrogen and methane extend around the moon 10 times as far into space as Earth's atmosphere, sometimes falling to the surface in the form of methane rain. This atmosphere makes it one of the best potential candidates for hosting life. Titan is larger than the planet Mercury , though not nearly as massive. It hosts many hydrocarbon-filled lakes as well as extremely tall mountains, with the largest one rising to nearly 11,000 feet .

This moon is the only one to have a landing craft arrive on its surface, when the Cassini mission sent the Huygens lander there in 2005. Wispy terrain reflects sunlight brightly in the lower left of this Cassini image of the northern latitudes of Saturn's moon Dione. Image taken December 20, 2010. Credit: NASA/JPL/Space Science Institute Dione Dione is thought to be a dense rocky core surrounded by water-ice. The tidally locked moon is heavily cratered not on its leading side but on its back side. Astronomers think a collision could have spun the moon on its axis. The moon hosts a thin oxygen atmosphere and may have a liquid ocean beneath its surface . Enceladus Enceladus contains more than 100 geysers at its south pole. Tidal heating causes portions of the icy planet to melt, spewing icy material into space from its "tiger stripes." The tiny bits of ice travel together to create Saturn's E ring. The satellite's icy surface makes it one of the brightest objects in the solar system. The moon has a subsurface ocean that may be friendly to life.

Hyperion Hyperion was the last of the major satellites to be discovered. Hyperion is a small moon with an irregular appearance. The flattened object resembles an elongated potato rather than a sphere, a form that may have been created when an impact demolished a larger moon long ago. Hyperion has a spongy shape, possibly due to its low density and porous surface. Impacts seem to be absorbed by the moon, and most of the ejecta is thrown into space. The equatorial ridge of Iapetus can reach heights of up to 12 miles (20 km). This image reveals mountains only about half that height. Credit: NASA/JPL/Space Science Institute Iapetus Iapetus features light and dark contrasts on its surface, giving the moon a yin-yang shape. Dark hydrocarbons falling to the moon long ago, perhaps from the nearby moon Phoebe, may have had more time to absorb more heat, gradually growing and spreading over time. Iapetus has a walnut-like shape, with its center bulging outward, and a ridge running around its equator. The moon also contains some of the highest mountains in the solar system, which may have been material from another moon .

Scientists are studying ice movements (such as landslides) to do comparative work with these types of features on Earth. Mimas Mimas has a gaping crater that gives the rocky moon a strong resemblance to fictional Death Star in the "Star Wars" movies. The impact stands out despite the fact that Mimas is one of the most heavily cratered bodies in the solar system, with overlapping impacts covering the surface. The smallest and closest orbiting of Saturn's major moons, Mimas cleared the gap known as the Cassini division between two of the planet's rings. Mimas is made up primarily of water-ice, but despite its proximity to the planet (and the resulting tidal heating that should occur), the surface of the moon remains unchanged; none of the ice seems to be melting, though such melting occurs on other, more distant moons. It is possible that there is a liquid ocean beneath its surface , although scientists say that an oval-shaped core could also explain some of Mimas' libration movements. This raw image of Saturn's icy moon Rhea was taken on March 10, 2013 by NASA's Cassini spacecraft, and received on Earth March 10, 2013.

The camera was pointing toward Rhea at approximately 174,181 miles (280,317 kilometers) away. Credit: NASA/JPL/Space Science Institute Rhea Rhea is a heavily cratered moon and lacks a core at its center. Instead, the entire body is composed of ice, with traces of rock mixed in, causing it to resemble a dirty snowball. The second largest of the planet's major moons, Rhea is still rather small, about half the size of Earth's moon. The satellite contains a faint oxygen atmosphere, about 5 trillion times less dense than the one found on Earth, but the only known oxygen atmosphere in the solar system. Radiation from Saturn's magnetosphere could release oxygen and carbon dioxide from the icy surface. Tethys Tethys travels close to Saturn and feels the gravitational pull of the planet. The heat from Saturn may allow the moon's icy surface to melt slightly, filling in craters and other signs of impact. Made up almost entirely of water ice, the surface is highly reflective. A large trench crosses the moon, running diagonally from its north to south pole and spanning three-quarters of the satellite's circumference.

A large crater on the other side of the moon covers nearly two-fifth of the moon's diameter and is nearly the size of Mimas. Scientists have found strange red arcs on the moon and are still struggling to explain how the arcs got there. The minor moons The smaller named moons of Saturn are as follows: 9. Erriapus Saturn's satellites, moons – groups, Trojan moons, provisional moons Iapetus / nasa.gov Iapetus — (eye-APP-eh-tuss), is the last of Saturn's satellites. It's Yin Yang of a leading hemisphere of a dark albedo (reflectivity) of 0.3 to 0.5 and its trailing hemisphere of a brighter albedo of 0.5 to 0.6. Around the equator of this satellite is a range of mountains making it look like two "helmets" put together. It is believed that Iapetus is, like Rhea, is three quarters ice and one quarter rock. Saturn's Moons Note: Many of Saturn's moons are located in its 9 rings. These rings were named using the letters of the alphabet as they were discovered, and so they are not in order.

Going from the planet out these rings are D, C, B, A, F, G, and E.

Phoebe / nasa.gov Norse Group — the largest group of Saturn's moon groups is the Norse Group consisting of 13 major moons (Phoebe, Greip, Jarnsaxa, Mundilfari, Suttungr, Hati, Thrymr, Aegir, Fenrir, Surtur, Ymir, Loge, and Fornjot), two subgroups Skathi (Skathi, Skoll, Hyrrokkin, Bergelmir, Farbauti, Kari, S/2006 S 3, and S/2006 S 1) and Narvi (Narvi and Bestla), and 6 provisional moons that are not classified under the 2 subgroups (S/2007 S 2, S/2004 S 13, S/2004 S 17, S/2004 S 12, S/2004 S 7, S/2007 S 2, and S/2007 S 3). These moons follow a retrograde (opposite direction of the parent) orbit.

Inuit Group — consist of 5 moons (Kiviuq, Ijiraq, Paaliaq, Siarnaq, and Tarqeq) which follow a prograde (same direction as the parent) orbit around Saturn. The inclination is approximately 40 to 50 degrees around Saturn, meaning their elliptical orbit around Saturn is at a 40 to 50-degree angle. Their eccentricities (degree of orbit compared to circular or elliptical, 0 would be circular, 1 and up are elliptical) are at .15 to .48. Gallic Group — consist of 4 moons (Albiorix, Bebhionn, Erriapus, and Tarvos) that follow a prograde orbit around Saturn. They have an inclination of between 35 and 40 degrees and their eccentricities are at approximately .53. Aegaeon — is relatively small, at only 1/3 of a mile wide, and located in Saturn's partial G ring and does not belong to any family group. It is believed that this "moonlet" is the main source of the ring. Aegaeon is Saturn's smallest moon and is elongated in shape.

Aegaeon's density is similar to water ice and it has an albedo of .15. Anthe — orbiting between Mimas and Enceladus, Anthe is approximately 1 mile in diameter. There is strong belief that Anthe (along with Methone and Pallene) may actually be parts of either Mimas or Enceladus that had broken off. Another belief is that they all belonged to a larger collection of asteroids that got caught in Saturn's pull. Methone / nasa.gov Methone — located between Mimas and Enceladus, Methone is approximately 1 mile (1.6 km) in size and may have been (along with Pallene and Anthe) apart of either Mimas or Enceladus or, all five moons may have been part of a swarm of asteroids that passed through. Methone's orbital path around Saturn takes approximately 24 hours for it to complete. Pallene — is located in orbit between Mimas and Enceladus along with Methone and Anthe.

This little moon is in a dynamic relationship with Methone and Anthe, basically, the three moons along with Mimas and Enceladus assist one another in their rotation and movement. The moon is approximately 3 miles (4 km) across and takes about 27 hours to complete its orbit around Saturn. Prometheus / wikimedia.org Prometheus — occupies the inner part of Saturn's F-ring. Extremely irregular and potato like in its shape it is covered in craters that are up to 12 miles (20 km) in size. It is believed that its surface is porous because of its low density. It Is approximately 26 miles (43 km) in size and has an orbital time of about 14 hours around the planet. Saturn's Trojan Moons A Trojan Moon is a moon that shares an orbit with another, larger moon. They move in a synchronized fashion and never collide with one another. The "Trojan" can either be trailing or leading the larger moon it shares it's orbit with. Space Today Online - Exploring Saturn - The Planet Saturn by Cassini Saturn is the second largest planet in our Solar System. It is the sixth planet outward from the Sun.

At a distance of some 900 million miles, Saturn is almost twice as far from the Sun as the planet Jupiter. From Saturn, the Sun appears ten times smaller than it appears from Earth. An average area on Earth receives 90 times the amount more sunlight than the same area on Saturn. Being farther from the Sun, Saturn is much colder than Jupiter, with an average temperature around –285°F. Somewhat like our Solar System of which it is a part, Saturn has its own system, including spectacular rings and the second greatest collection of moons in the Solar System including the second largest moon in the Solar System. The planet is named for the ancient Roman god of agriculture. The English word Saturday comes from the word Saturn. Take a look. Saturn is seen easily without a telescope. In fact, people have being seeing Saturn in the nighttime sky since before history. In 1610, the Italian astronomer Galileo was the first to observe Saturn with a telescope. In 1655, Dutch physicist Christiaan Huygens spotted the first moon of Saturn. In 1656, Huygens figured out the shape of the rings around Saturn.

To honor his work, the Titan lander carried into the Saturn system by the Cassini spacecraft in 2004 was named for Huygens. The lander descended onto Titan in 2005. Today, Saturn's rings and larger satellites can be seen with a small telescope. By the way, it's easy to identify Saturn as a planet because its light is steady. It doesn't twinkle like the stars. What Is It Made Of? It is not a rock like Earth. Saturn is not solid at all. It doesn't have a surface. You couldn't land there because there is nothing solid to land on. If there is something at the center, it might be a teeny core of rock surrounded by a liquid and then smothered by the very deep atmosphere. Saturn is a giant cloud of mostly hydrogen and helium gases. Gravity, the same force that brings things down to Earth, holds the gases of Jupiter together. Billions of years ago, there may have been several huge clouds of gas that came together. As the combined cloud got bigger, it gathered up more gas. The larger it grew, the stronger its gravity became. Saturn may not have land, but it does have weather.

With clouds swirling through the atmosphere ahead of 1,000 mph winds, storm patterns could be ever-changing. Big ol' gas bag. Astronomers refer to four of the Solar System's outer planets as gas giants – Jupiter, Saturn, Uranus and Neptune. Saturn, which formed more than four billion years ago, is mostly hydrogen and helium gases. There are lesser amounts of methane and ammonia. Saturn is a big ball of gas almost 75,000 miles in diameter held together by the pull of gravity. Hydrogen and helium also are the main gases in the Sun. While almost as big in size as Jupiter, Saturn's mass is only 30 percent of Jupiter's mass. And its density is lowest in the Solar System. It's so low, in fact, that it would float in a bathtub if only we had a big enough tub. Saturn doesn't have a solid surface of hard ground that we could walk on. What we see through telescopes is not a surface, but actually the top layer of a cloud of ammonia ice crystals. Saturn's interior certainly is quite hot. The core temperature probably is 21,150°F.

In fact, Saturn radiates more energy into space than it receives from the Sun. Saturn's core may be rocky and about the size of the planet Earth. Above that hard core may be a liquid metallic hydrogen layer and a molecular hydrogen layer. Various ices also may be present. Saturn looks yellow to us because it is reflecting light from the Sun. Small amounts of impurities within the ammonia cause the other colors we see in Saturn's cloud tops. Winds are extreme at Saturn's equator where they can reach speeds greater than 1,100 mph. By comparison, the strongest hurricane winds on Earth reach 246 mph. Saturn's winds combine with heat from the planet's interior to spawn the yellow and gold bands we see in the planet's atmosphere. The clouds tops are quite cold at around –400°F. Interestingly, the ammonia might be frozen and rain down from the clouds at –300°F.. The planet is surrounded by an enormous magnetic field. Like a huge bubble, this magnetosphere traps and holds electric particles near the planet. The planet spins so fast, a day on Saturn lasts just over 10 hours.

Because the planet is so far from the center of the Solar System, it takes Saturn almost 30 years to make a trip around the Sun. About Moons... A moon is a natural satellite rotating around a planet. While moons vary in size, each moon is much smaller than its planet. Several moons are larger than the planet Pluto and two moons are larger than the planet Mercury. There also are many small moons that may be asteroids captured by their planets. Only Mercury and Venus do not have any moons. By comparison, Earth has one moon and Mars has two. Jupiter has the most moons of any planet. Saturn is second. Pictures taken by the Hubble Space Telescope suggest there may be even more moons around those outer planets. LIST OF ALL PLANETS AND THEIR MOONS »» The Moons.

Saturn's moons are Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, Mimas, Hyperion, Prometheus, Pandora, Phoebe, Janus, Epimetheus, Helene, Telesto, Calypso, Atlas, Pan, Ymir, Paaliaq, Siarnaq, Tarvos, Kiviuq, Ijiraq, Thrym, Skadi, Mundilfari, Erriapo, Albiorix, Suttung, and others yet to receive names. list of saturn moons » When the Cassini spacecraft from Earth arrived at Saturn in 2004, it promptly found two previously unseen moons. They turned out to be the smallest bodies seen around the ringed planet up to that time. The tiny natural satellites are about 2 miles and 2.5 miles in diameter. That's smaller than the city of Boulder, Colorado. Previously, the smallest moons seen around Saturn were are about 12 miles across. The moons are 120,000 miles and 131,000 miles from the center of planet Saturn between the moons Mimas and Enceladus.

The newly discovered bodies were labeled S/2004 S1 and S/2004 S2. Later, they will be given names. The NASA JPL team wondered if S/2004 S1 might not be an object called S/1981 S14 that had turned up in a 1981 Voyager image. Each of Saturn's known moons is unique. Here are some examples: Enceladus has a very bright surface and may have active water volcanoes. Tethys has a canyon running three-quarters of the way around its surface. It once may have split almost in half. Dione and Rhea have wispy white markings on one side. Mimas has an enormous crater — a hole caused by a meteorite. The moon may be responsible for the emptiness of the so-called Cassini division between rings. Hyperion is oddly shaped and the length of its day is constantly changing. Iapetus is half bright and half dark. Pan is a tiny moon only about 12 miles in diameter. It is between rings in the so-called Encke Division. Atlas, Prometheus and Pandora are shepherd moons because they keep rings in place. Titan is Saturn's largest moon.

It's larger in diameter than the planet Mercury and larger and more massive than the planet Pluto. In fact, astronomers once listed Titan as the largest moon in the Solar System, but more precise measurements revealed that it has a very thick atmosphere around it and Jupiter's moon Ganymede has a larger solid surface. Titan was the prime target of the Cassini-Huygens mission. Saturn's rings by Cassini The Rings. The big planet is known for its dramatic rings. People often refer to it when they say, "the ringed planet." Of course, some other planets have rings. Why are there rings around planets? It's not clear. Rings are not stable so they must rebuild themselves regularly. Saturn's current set of rings probably are only a few hundred million years old. There are several rings around Saturn, each different from the others. list of saturn rings » Three rings known as A, B and C can be seen from Earth: The rings that astronomers have labeled A and B stand out, while another ring labeled C is faint. The gap between the A and B is referred to as the Cassini division.

A faint gap in the outer part of A is known as the Encke Division, although German astronomer Johann Franz Encke may never have seen the gap. The rings are not perfectly circular and the gaps between the rings are not entirely empty. If you were to take a close-up look at a ring, you would see a flood of pieces from inches to feet in size, each in an independent orbit. There might be some chunks as large as a mile or so across. You also would see the ring is very thin. While it may be 150,000 miles across, it might be only half a mile thick. There's really not much in the ring. While it appears expansive, compressing the ring's material would result in a clump only about 60 miles in diameter. The ring's particles probably are water ice with some small ice-covered rocks. Voyager saw spokes and braids in the rings. Cassini has seen spirals. These mysteries may relate to Saturn's magnetic field. Four previously unknown, faint rings turned up in photographs sent back the Voyager spacecraft in the 1980s. The outermost ring, labeled F, actually is several smaller rings with some knots of clumped material.

Could the knots be tiny moons? Saturn's rings were believed to be unique until 1977 when very faint rings were discovered around the planet Uranus. Shortly after that, other rings were seen around the planets Jupiter and Neptune. Saturn Closest to Earth The planet Saturn was relatively close to Earth on December 31, 2003, when it was about 746 million miles away. The sunlight reflected from the planet caused it to appear brighter than usual to observers on Earth. Saturn won't be that close to Earth again until 2032. Robot Explorers. Saturn has been visited by several interplanetary probes from Earth. The first was Pioneer 11 in 1979. Later, Saturn was visited by twin spacecraft from Earth known as the Voyagers. In fact, most of what we knew about Saturn and its system of moons and rings for two decades was learned when Voyager 1 flew by Saturn in 1980 and when Voyager 2 flew by Saturn in 1981. The robot explorers Cassini and Huygens arrived in the Saturn system on July 1, 2004.

Huygens did its job in 2005 while Cassini will work among the moons and rings until at least 2008. Now we are learning a great deal more about the beautiful ringed planet. List of Moons and Rings. Here the natural satellites of Saturn and the rings around the planet: Moons of Saturn Saturn: The Satellite System Saturn The Satellite System Saturn has 61 confirmed natural satellites, 52 of which are named. Because the increasing number of satellites makes it difficult to continue to name them after Greek Titans, a scheme was adopted for the outer satellites. These are now named after the giants of other cultures: Inuit, Norse, and Gallic. The satellites may be divided into nine groups for convenience.

In the order of their distance from Saturn, the groups are shepherd (satellites whose orbit is within or just beyond Saturn's ring system), co-orbital (two satellites that share the same orbit and trade positions within it on a regular basis), inner large (large satellites within the E ring), Alkyonide (small satellites within the inner large group), Trojan (satellites that are co-orbital at Lagrangian points), outer large (large satellites beyond the E ring), and Inuit, Norse, and Gallic (each a group of outer satellites that have similar orbits). Five of the six confirmed shepherd satellites, Pan , Daphnis, Atlas , Prometheus , and Pandora , are named. The co-orbital group comprises Epimetheus and Janus , but the shepherds Prometheus and Pandora also share an orbit. The inner large group comprises four satellites, Mimas , Enceladus , Tethys , and Dione ; the three Alkyonides (Methone, Anthe, and Pallene) have orbits between Mimas and Enceladus. The Trojan group, also found within the inner large group, comprises four satellites, Telesto , Calypso , Helene , and Polydeuces.

The outer large group comprises four satellites, Rhea , Titan , Hyperion , and Iapetus . The Inuit group comprises five satellites, Kiviuq, Ijiraq, Paaliaq, Siarnaq, and Tarqeq. Of the 29 satellites comprising the Norse group, only 21 are named: Phoebe , Skathi, Skoll, Greip, Hyrrokkin, Jamsaxa, Mundilfari, Bergelmir, Narvi, Suttungr, Hati, Farbauti, Thrymr, Aegir, Bestia, Fenrir, Surtur, Kari, Ymir, Loge, and Fornjot. The Gallic group consists of four satellites, Albiorix, Bebhionn, Erriapus, and Tarvos. Almost all of Saturn's inner moons form a regular system of satellites; that is, their orbits are nearly circular and lie in the equatorial plane of the planet; almost all of the outer moons' orbits are inclined.

Except for Hyperion, which has a chaotic orbit, and Phoebe, all the satellites are believed to have synchronous orbits; that is, their orbital and rotational periods are the same, so that they always keep the same face turned toward Saturn. The largest satellite, Titan, is 3,200 mi (5,150 km) in diameter and has the size and cold temperatures necessary to retain an atmosphere; it is the only natural satellite in the solar system with a substantial atmosphere. Saturn has six major icy satellites that can be easily seen through earth-based telescopes. The most prominent feature of heavily cratered Mimas, the innermost of the six, is a large impact crater about one third the diameter of the satellite. Certain broad regions of Enceladus are uncratered, indicating geological activity that has resurfaced the satellite within the last 100 million years. Tethys also has a very large impact crater, as well as an extensive series of valleys and troughs that stretches three quarters of the way around the satellite.

Both Dione and Rhea have bright, heavily cratered leading hemispheres and darker trailing hemispheres with wispy streaks that are thought to be produced by deposits of ice inside surface troughs or cracks. Iapetus, the outermost of the large icy satellites, has a dark leading hemisphere and a bright trailing hemisphere. The remaining satellites are smaller. The two largest of these, the dark-surfaced Phoebe and the irregularly shaped Hyperion, orbit far from the planet; the Norse group of satellites orbit with retrograde motion , i.e., opposite to that of the planet's rotation. The smallest satellites, less than c.6 mi (10 km) in diameter, include Daphnis, the Alkyonides, Polydeuces, some of the Inuit and Gallic groups, and nearly all of the Norse group. Sections in this article: The moons of Saturn The moons of Saturn September 14, 2015 by Matt Williams, Universe Today Saturn and its largest moons. Credit: NASA/JPL/SSI Saturn is well known for being a gas giant, and for its impressive ring system.

But would it surprise you to know that this planet also has the second-most moons in the Solar System, second only to Jupiter? Yes, Saturn has at least 150 moons and moonlets in total, though only 53 of them have been given official names. Most of these moons are small, icy bodies that are little more than parts of its impressive ring system. In fact, 34 of the moons that have been named are less than 10 km in diameter while another 14 are 10 to 50 km in diameter. However, some of its inner and outer moons are among the largest and most dramatic in the Solar System, measuring between 250 and 5000 km in diameter and housing some of greatest mysteries in the Solar System. Discovery and Naming: Prior to the invention of telescopic photography, eight of Saturn's moons were observed using simple telescopes. The first to be discovered was Titan, Saturn's largest moon , which was observed by Christiaan Huygens in 1655 using a telescope of his own design.

Between 1671 and 1684, Giovanni Domenico Cassini discovered the moons of Tethys, Dione, Rhea and Iapetus – which he collectively named the "Sider Lodoicea" (Latin for "Louisian Stars", after King Louis XIV of France). In 1789, William Herschel discovered Mimas and Enceladus, while father-and-son astronomers W.C Bond and G.P. Bond discovered Hyperion in 1848 – which was independently discovered by William Lassell that same year. By the end of the 19th century, the invention of long-exposure photographic plates allowed for the discovery of more moons – the first of which Phoebe, observed in 1899 by W.H. Pickering. In 1966, the tenth satellite of Saturn was discovered by French astronomer Audouin Dollfus, which was later named Janus. A few years later, it was realized that his observations could only be explained if another satellite had been present with an orbit similar to that of Janus.

This eleventh moon was later named Epimetheus, which shares the same orbit with Janus and is the only known co-orbital in the Solar System. By 1980, three additional moons were discovered and later confirmed by the Voyager probes. They were the trojan moons (see below) of Helene (which orbits Dione) as well as Telesto and Calypso (which orbit Tethys). The study of the outer planets has since been revolutionized by the use of unmanned space probes. This began with the arrival of the Voyager spacecraft to the Cronian system in 1980-81, which resulted in the discovery of three additional moons – Atlas, Prometheus, and Pandora – bringing the total to 17. By 1990, archived images also revealed the existence of Pan. This was followed by the Cassini-Huygens mission, which arrived at Saturn in the summer of 2004. Initially, Cassini discovered three small inner moons, including Methone and Pallene between Mimas and Enceladus, as well as the second Lagrangian moon of Dione – Polydeuces.

In November of 2004, Cassini scientists announced that several more moons must be orbiting within Saturn's rings. From this data, multiple moonlets and the moons of Daphnis and Anthe have been confirmed. The study of Saturn's moons has also been aided by the introduction of digital charge-coupled devices, which replaced photographic plates by the end of the 20th century. Because of this, ground-based telescopes have begun to discovered several new irregular moons around Saturn. In 2000, three medium-sized telescopes found thirteen new moons with eccentric orbits that were of considerable distance from the planet. In 2005, astronomers using the Mauna Kea Observatory announced the discovery of twelve more small outer moons. In 2006, astronomers using Japan's Subaru Telescope at Mauna Kea reported the discovery of nine more irregular moons. In April of 2007, Tarqeq (S/2007 S 1) was announced, and in May of that same year, S/2007 S 2 and S/2007 S 3 were reported.

The modern names of Saturn's moons were suggested by John Herschel (William Herschel's son) in 1847. In keeping with the nomenclature of the other planets, he proposed they be named after mythological figures associated with the Roman god of agriculture and harvest – Saturn, the equivalent of the Greek Cronus. In particular, the seven known satellites were named after Titans, Titanesses and Giants – the brothers and sisters of Cronus. In 1848, Lassell proposed that the eighth satellite of Saturn be named Hyperion after another Titan. When in the 20th century, the names of Titans were exhausted, the moons were named after different characters of the Greco-Roman mythology, or giants from other mythologies. All the irregular moons (except Phoebe) are named after Inuit and Gallic gods and Norse ice giants. Inner Large Moons: Saturn's moons are grouped based on their size, orbits, and proximity to Saturn. The innermost moons and regular moons all have small orbital inclinations and eccentricities and prograde orbits.

Meanwhile, the irregular moons in the outermost regions have orbital radii of millions of kilometers, orbital periods lasting several years, and move in retrograde orbits. Saturn's Inner Large Moons, which orbit within the E Ring (see below), include the larger satellites Mimas, Enceladus, Tethys, and Dione. These moons are all composed primarily of water ice, and are believed to be differentiated into a rocky core and an icy mantle and crust. With a diameter of 396 km and a mass of 0.4×1020 kg, Mimas is the smallest and least massive of these moons. It is ovoid in shape and orbits Saturn at a distance of 185,539 km with an orbital period of 0.9 days. Saturn’s moons (from left to right) Janus, Pandora, Enceladus, Mimas and Rhea. Rhea is on top of Saturn. Credit: NASA/JPL-Caltech/Space Science Institute Enceladus, meanwhile, has a diameter of 504 km, a mass of 1.1×1020 km and is spherical in shape.

It orbits Saturn at a distance of 237,948 km and takes 1.4 days to complete a single orbit. Though it is one of the smaller spherical moons, it is the only Cronian moon that is endogenously active – and one of the smallest known bodies in the Solar System that is geologically active. This results in features like the famous "tiger stripes" – a series of continuous, ridged, slightly curved and roughly parallel faults within the moon's southern polar latitudes. Large geysers have also been observed in the southern polar region that periodically release plumes of water ice, gas and dust which replenish Saturn's E ring. These jets are one of several indications that Enceladus has liquid water beneath it's icy crust, where geothermal processes release enough heat to maintain a warm water ocean closer to its core. With a geometrical albedo of more than 140%, Enceladus is one of the brightest known objects in the Solar System. At 1066 km in diameter, Tethys is the second-largest of Saturn's inner moons and the 16th-largest moon in the Solar System.

The majority of its surface is made up of heavily cratered and hilly terrain and a smaller and smoother plains region. Its most prominent features are the large impact crater of Odysseus, which measures 400 km in diameter, and a vast canyon system named Ithaca Chasma – which is concentric with Odysseus and measures 100 km wide, 3 to 5 km deep and 2,000 km long. With a diameter and mass of 1,123 km and 11×1020 kg, Dione is the largest inner moon of Saturn. The majority of Dione's surface is heavily cratered old terrain, with craters that measure up to 250 km in diameter. However, the moon is also covered with an extensive network of troughs and lineaments which indicate that in the past it had global tectonic activity. Large Outer Moons: The Large Outer Moons, which orbit outside of the Saturn's E Ring, are similar in composition to the Inner Moons – i.e. composed primarily of water ice and rock.

Of these, Rhea is the second largest – measuring 1,527 km in diameter and 23×1020 kg in mass – and the ninth largest moon of the Solar System. With an orbital radius of 527,108 km, it is the fifth-most distant of the larger moons, and takes 4.5 days to complete an orbit. Like other Cronian satellites, Rhea has a rather heavily cratered surface, and a few large fractures on its trailing hemisphere. Rhea also has two very large impact basins on its anti-Saturnian hemisphere – the Tirawa crater (similar to Odysseus on Tethys) and an as-yet unnamed crater – that measure 400 and 500 km across, respectively. A composite image of Titan’s atmosphere, created using blue, green and red spectral filters to create an enhanced-color view. Credit: NASA/JPL/Space Science Institute At 5150 km in diameter, and 1,350×1020 kg in mass, Titan is Saturn's largest moon and comprises more than 96% of the mass in orbit around the planet.

Titan is also the only large moon to have its own atmosphere, which is cold, dense, and composed primarily of nitrogen with a small fraction of methane. Scientists have also noted the presence of polycyclic aromatic hydrocarbons in the upper atmosphere, as well as methane ice crystals. The surface of Titan, which is difficult to observe due to persistent atmospheric haze, shows only a few impact craters, evidence of cryovolcanoes, and longitudinal dune fields that were apparently shaped by tidal winds. Titan is also the only body in the Solar System beside Earth with bodies of liquid on its surface, in the form of methane–ethane lakes in Titan's north and south polar regions. With an orbital distance of 1,221,870 km, it is the second-farthest large moon from Saturn, and completes a single orbit every 16 days. Like Europa and Ganymede, it is believed that Titan has a subsurface ocean made of water mixed with ammonia, which can erupt to the surface of the moon and lead to cryovolcanism. Hyperion is Titan's immediate neighbor. At an average diameter of about 270 km, it is smaller and lighter than Mimas.

It is also irregularly shaped and quite odd in composition. Essentially, the moon is an ovoid, tan-colored body with an extremely porous surface (which resembles a sponge). The surface of Hyperion is covered with numerous impact craters, most of which are 2 to 10 km in diameter. It also has a highly unpredictable rotation, with no well-defined poles or equator. At 1,470 km in diameter and 18×1020 kg in mass, Iapetus is the third-largest of Saturn's large moons. And at a distance of 3,560,820 km from Saturn, it is the most distant of the large moons, and takes 79 days to complete a single orbit. Due to its unusual color and composition – its leading hemisphere is dark and black whereas its trailing hemisphere is much brighter – it is often called the "yin and yang" of Saturn's moons. The moons of Saturn, from left to right: Mimas, Enceladus, Tethys, Dione, Rhea; Titan in the background; Iapetus (top) and Hyperion (bottom).

Credit: NASA/JPL/Space Science Institute Irregular Moons: Beyond these larger moons are Saturn's Irregular Moons. These satellites are small, have large-radii, are inclined, have mostly retrograde orbits, and are believed to have been acquired by Saturn's gravity. These moons are made up of three basic groups – the Inuit Group, the Gallic Group, and the Norse Group. The Inuit Group consists of five irregular moons that are all named from Inuit mythology – Ijiraq, Kiviuq, Paaliaq, Siarnaq, and Tarqeq. All have prograde orbits that range from 11.1 to 17.9 million km, and from 7 to 40 km in diameter. They are all similar in appearance (reddish in hue) and have orbital inclinations of between 45 and 50°. The Gallic group are a group of four prograde outer moons named for characters in Gallic mythology -Albiorix, Bebhionn, Erriapus, and Tarvos. Here too, the moons are similar in appearance and have orbits that range from 16 to 19 million km.

Their inclinations are in the 35°-40° range, their eccentricities around 0.53, and they range in size from 6 to 32 km. Last, there is the Norse group, which consists of 29 retrograde outer moons that take their names from Norse mythology. These satellites range in size from 6 to 18 km, their distances from 12 and 24 million km, their inclinations between 136° and 175°, and their eccentricities between 0.13 and 0.77. This group is also sometimes referred to as the Phoebe group, due to the presence of a single larger moon in the group – which measures 240 km in diameter. The second largest, Ymir, measures 18 km across. Within the Inner and Outer Large Moons, there are also those belonging to Alkyonide group. These moons – Methone, Anthe, and Pallene – are named after the Alkyonides of Greek mythology, are located between the orbits of Mimas and Enceladus, and are among the smallest moons around Saturn. Saturn’s moon of Enceladus.

Credit: NASA/JPL/Space Science Institute Some of the larger moons even have moons of their own, which are known as Trojan moons. For instance, Tethys has two trojans – Telesto and Calypso, while Dione has Helene and Polydeuces. Formation: The two sides of Iapetus, “Saturn’s yin yang moon”. Credit: NASA/JPL It is thought that Saturn's moon of Titan, its mid-sized moons and rings developed in a way that is closer to the Galilean moons of Jupiter. In short, this would mean that the regular moons formed from a circumplanetary disc, a ring of accreting gas and solid debris similar to a protoplanetary disc. Meanwhile, the outer, irregular moons are believed to have been objects that were captured by Saturn's gravity and remained in distant orbits. Dione’s heavily cratered surface, as observed by the Cassini flyby in June, 2015. Credit: NASA/JPL However, there are some variations on this theory. In one alternative scenario, two Titan-sized moons were formed from an accretion disc around Saturn; the second one eventually breaking up to produce the rings and inner mid-sized moons.

In another, two large moons fused together to form Titan, and the collision scattered icy debris that formed to create the mid-sized moons. However, the mechanics of how the moon's formed remains a mystery for the time being. With additional missions mounted to study the atmospheres, compositions and surfaces of these moons, we may begin to understand where they truly came from. Saturn’s rings and moons Credit: NASA Much like Jupiter, and all the other gas giants, Saturn's system of satellites is extensive as it is impressive. In addition to the larger moons that are believed to have formed from a massive debris field that once orbited it, it also has countless smaller satellites that were captured by its gravitational field over the course of billions of years. One can only imagine how many more remain to be found orbiting the ringed giant.

Question: 'Atlas', 'Mimas' and 'Calypso' are three of the satellites of which planet?
Answer: SATURN